venting gas tank?

[GMC3]

I relocated the tank to under the bed and want my filler to be mounted in the bed floor. Was thinking of using one of those flush mount boat style filler necks, but the gas cap is not vented. can I use that smaller hose (3/8)? that usually hooks into the side of the regular filler necks, as my vent? or do I have to use some sort of check valve on it? Or any other suggestions? THanks

[Longhorn Man]

the one you see on filler necks isn't really a vent, more of a burp tube. To vent, it would have to exit after the fuel cap.
You could run a vent with a breather on it, like on a rear axle, so fumes could get out, but no water gets in, however, you'd end up with lots of fumes, esp if it was in a garage. The only way to do it, would to install a charchol canister, plumbed both to the tank, and to the intake to purge the fumes. It's a good idea, and one of the few emissons control items that doesn't rob power and is a good idea to install.